A conventional IC card comprises radio frequency identification unit or units having built-in integrated circuit or circuits, a carrier layer to carry said identification unit or units, said layer comprising a core layer and/or an inner layer, and an upper protective layer and a lower protective layer for protecting the upper face and the lower face of the carrier layer, respectively. This laminate exchanges information between the integrated circuit or circuits and external units through external contact terminals provided on, for example, said upper protective layer, or a communication antenna which is installed on the carrier layer.
Such a conventional contact type IC card provided with external contact terminals performs exchange of electronic signal information with external read-and-write units (reader/writer), or receives power supply, through the external contact terminals provided, for example, on said upper protective layer.
A non-contact type IC card which is installed with a communication antenna (or simply, “antenna”) receives power supply and exchanges electronic signal information between its integrated circuit module of, e.g., radio frequency identification integrated circuits, and external reader/writers, through the antenna installed on its carrier layer.
Such non-contact type IC cards are further classified, according to the distance between the involved integrated circuit enclosed laminate and reader/writers, into close coupling type (within 2 mm), proximity coupling type (within 10 cm), vicinity coupling type (within 70 cm) and distance coupling type (more than 70 cm). In general, short waves are used for the close coupling and proximity coupling types which emit radio waves over short ranges; long waves are used for vicinity coupling type and microwaves, for distance coupling type.
Various methods for forming such a non-contact type IC card with an antenna installed therein have been proposed. As methods for forming the antenna, a method of forming an antenna by partially removing a previously installed metallic layer by such means as etching, a method of forming an antenna by partially installing a metallic layer, a method of forming an antenna by using a conductive ink and a method of forming an antenna by winding a metallic thin wire into a coil are known.
Examples of prior art disclosing these antenna-forming methods include JP Patent Publication Hei 11(1999)-134461A to Horio and its U.S. counterpart, U.S. Pat. No. 6,160,526; JP Patent Publication Hei 10(1998)-320519A to Ikefuji, et al. and its EP counterpart, EP 1014301A1; JP Patent Publication Hei 8(1996)-287208A to Orihara, et al. and its US counterpart, U.S. Pat. No. 5,705,852; JP Patent Publication 2002-074301A to Okamura, et al. and its US counterpart, US 2002/24475; JP Patent Publication 2000-251047A to Hayashi, et al. and its EP counterpart, EP 1033778A2; and JP Patent Publication 2000-105810A to Hayashi, et al. and its EP counterpart, EP 1039411A1. Disclosures of those references can be referred to, for further explanation of their techniques.
On the other hand, retroreflective sheetings and retroreflective molded articles which are installed with a multiplicity of retroreflective units (hereafter collectively referred to as “retroreflective sheeting”) are used for traffic signs, safety instruments, reflective stickers, commercial signboards and optical-sensor reflectors, particularly for safety and display instruments in the nighttime, which reflect light toward their light sources.
In such retroreflective sheeting, a multiplicity of micro glass bead type or cube corner prism type retroreflective units are installed inside of the sheeting, which are so designed that entrance light into the retroreflective units from a light source is reflected once again toward the light source.
For example, U.S. Pat. No. 4,025,159 to McGrath discloses retroreflective sheeting using micro glass bead type retroreflective units; U.S. Pat. No. 4,588,258 to Hoopman discloses a retroreflective sheeting using cube corner prism type retroreflective units; and U.S. Pat. No. 6,083,607 to Mimura discloses a retroreflective sheeting using cube corner prism type retroreflective units whose retroreflective angularity is improved.
Moreover, as a product equipped with retroreflective sheeting and a storage medium, JP Publication Sho 59(1984)-58630A to Tsukane, et al. discloses a product having a retroreflective layer constituted of glass beads and a magnetic recording layer.
JP Patent Announcement Hei 9(1997)-508983A (U.S. Pat. No. 5,621,571) to Bantli discloses an integrated retroreflective electronic display device. This patent discloses, according to descriptions in its specification, a retroreflective apparatus for visual and electromagnetic data communication, said apparatus comprising retroreflective sheeting for retroreflecting entrance light, said sheeting having visual informations thereon, and comprising a base sheet having a monolayer of retroreflective microspheres which are embedded in one of its surfaces and a regular light reflecting means which is disposed under said microspheres as spaced therefrom by a transparent material; antenna means for electromagnetic communication; and coupling means for allowing coupling to said antenna means.
JP Patent Announcement Hei 11(1999)-505050A (U.S. Pat. No. 5,608,391) to Bantli discloses an electronic license plate having a security identification device. According to disclosures of its specification, said patent discloses an electronic license plate architecture for use in an electronic vehicle communication system in which a plurality of remote traffic management stations communicate with the electronic license plate, comprising a license plate portion, including visual identification information and an identification means for storing restricted information, the restricted information including at least one type of vehicle identification information, and wherein the restricted information cannot be altered by the remote stations or by the vehicle; information means for storing unrestricted information, wherein the unrestricted information can be altered by at least one of the remote stations or by the vehicle; communication means, operatively connected to the identification means and to the information means, for processing communications with the remote stations; antenna means for transmitting and receiving the communications with the remote stations; and attachment means fixed to the vehicle for replaceably attaching the license plate portion on the vehicle, such that the license plate portion can be replaced without having to replace the information means.
JP Patent Publication Hei 4(1992)-229244A (U.S. Pat. No. 5,264,063) to Martin discloses a method for making a retroreflective microprismatic sheeting partially free from a metallic layer, said method comprising partially forming an adhesive layer on a metallic deposit layer formed on surfaces of retroreflective microprisms and removing a portion of said metallic layer which is unprotected by said adhesive layer. It also states that the partially provided adhesive layer (protective coating material) is desirably a pressure-sensitive adhesive which will not be unduly affected during a solvent treating step in later processing. Furthermore, as one of the methods for providing said layer, printing is named.
Furthermore, JP Patent Publication Hei 1(1989)-231004A (U.S. Pat. No. 4,801,193) to Martin discloses a method for making a retroreflective microprism sheet partially free from a metallic layer, which comprises forming a metallic deposit layer on surfaces of retroreflective microprisms, partially forming an adhesive layer on said metallic deposit layer and removing the metallic layer in the areas unprotected by said adhesive layer; and a method for making a retroreflective microprism sheet partially free from a metallic layer, which comprises partially installing a coating material on the retroreflective microprism surfaces, vapor depositing a metal thereon and removing the partially laid coating material.
Methods of removing vapor-deposited layers with laser also have been generally practiced.
U.S. Pat. No. 4,200,875 to Galanos discloses a method of forming an image on an exposed lens type retroreflective sheeting in accordance with a predetermined pattern by a laser method.
Internally illuminated retroreflective display devices are also known.
For example, JP Patent Publication Hei 1 (1989)-298395A (U.S. Pat. No. 4,592,023) to Bradshow discloses “an internally illuminated sign comprising an enclosure transmissive to light on at least one side, designated the front side, and cube corner retroreflective sheeting positioned to reflect light incident on the front of the sign, wherein the cube corner retroreflective sheeting:    (1) comprises a cover layer having a multiplicity of retroreflective cube corner elements and a base layer of transparent material bonded to the cover layer, and    (2) has areas, where the base layer has been bonded to the cover layer, which are:    (a) optically transparent to internal light with an angle of incidence greater than or equal to zero degrees and less than 90 degrees,    (b) interspersed among the areas occupied by cube corner elements, the proportion of such transparent areas to the total sheeting area and their arrangement relative to each other being fixed to allow viewing the sign by means of either internal illumination, retroreflected light, or both.”
JP Patent Publication Hei 2 (1990)-285301A (U.S. Pat. No. 5,122,902) to Benson discloses:
“an internally illuminated sign comprising a cover which is transmissive to light on at least one side, designated the front side, a cover which reflects light incident on the front of the sign and a retroreflective sheet which is positioned to reflect light incident on the front of the sign”, which sign uses “a partially transparent retroreflective article formed by three intersecting sets of parallel grooves, comprising a base, prismatic elements having lateral faces intersecting the base at base edges, and separation surfaces on the base, in which:    (a) each set of grooves has a groove side angle that is constant for that set;    (b) the separation surfaces are transparent, are bounded by the base edges of the lateral faces of the prismatic elements, lie between the prismatic elements in at least one of the grooves,and have, taken at any point along any groove in which they lay, curved cross sections taken across that groove.”
The present inventor, et al. also have disclosed, in EP 1542197A1, a retroreflective, internally illuminated sign which comprises an information display section having at least one flat or curved surface which retroreflects light coming from the front of said sign and transmits light from the interior of said sign; an illuminator disposed on the back of the information display section; and a housing enclosing and holding these information display section and illuminator, said sign being characterized in that
the retroreflective unit used in said information display section is a prismatic retroreflective unit in accordance with the principle of total internal reflection,
a large number of said prismatic retroreflective units are disposed in closest contact with each other to form a continuous retroreflective plane, and
at least the retroreflective part on the back of said large number of prismatic retroreflective units has no bonded area with other layers and has substantially no hermetically sealed structure.
Whereas, none of the foregoing patents discloses a retroreflective display device which is characterized by comprising at least a radio frequency identification unit with built-in integrated circuit or circuits and an optical retroreflective layer; more specifically a retroreflective display device in which the radio frequency identification unit has as enclosed therein radio frequency identification-type integrated circuit or circuits and communication antenna or antennas installed as connected to said radio frequency identification-type integrated circuit or circuits; still more specifically said communication antenna or antennas are formed on the reflective surface of the retroreflective elements.
The inventor of this invention has disclosed in U.S. Publication No. US2004/0218273A1 a retroreflective article with built-in integrated circuit or circuits which is characterized by comprising at least an integrated circuit module which encloses integrated circuits, an optical retroreflective element and a carrier layer for the foregoing, which is an improvement of the above-described invention.
The same invention also discloses a retroreflective integrated circuit-enclosing article in which said integrated circuit module encloses radio frequency identification-type integrated circuits and a communication antenna connected to said radio frequency identification-type integrated circuits is installed.
Those known IC cards are subject to such problems that the information stored in a contact-type IC card cannot be communicated without inserting the card into a reader/writer; and also with a non-contact-type IC card, it must approach to a distance near enough to allow identification of radio frequency, advance identification at a distance farther than the identifiable distance being impossible.
Furthermore, in case of a tollage settlement system (hereafter referred to as non-stop automatic toll system) by interactive radio communication using a non-contact type IC card on a toll road, there is a problem that it is usually necessary for each vehicle to install an in-vehicle read-and-write unit to assist the communication with the IC card, because of long distance lying between the IC card and an external reader/writer (road side communication antenna).
Until a vehicle approaches said reader/writer (road side communication antenna) near enough to allow the communication with the IC card on the vehicle, therefore, it is difficult for the reader/writer to distinguish vehicles carrying IC cards from those ordinary ones paying toll in cash. In particular, there is a problem at tollgates which concurrently run non-stop automatic toll system and collect tollage in cash, especially in the nighttime, that toll collectors cannot make visual distinguishment in advance. Because of this problem, automatic toll collection gates and cash collection gates have to be separated.
Those retroreflective display devices according to the present invention are used as signs on various commercial signboards and for various traffic uses such as road signs, construction signs, guide signs or vehicle number plates, to render the information displayed on these signs recognizable also in nighttime, and furthermore to enable still higher level information exchange by concurrently reading and writing electronic information stored in the integrated circuits which are enclosed in these signs with said radio frequency identification units.
In particular, when the technology of the present invention is applied to vehicle number plates, manufacture information of the vehicle bodies such as model, color, date of manufacture and information specific for each vehicle such as its owner, registration, tax payment, accident insurance, checkout and the like, can be comprehensively administered.
Therefore, introduction of the technology of the present invention enables to promote, solve or control various problems such as recently increasing theft of vehicles or number plates which now is becoming a social problem, nonpayment of taxes, failure to open accident insurance, negligence to have legal checkout and repair, and the like.
Again, application of the technology to traffic signs enables to supply such information as road regulations, construction information, guide information and the like to vehicle drivers via in-vehicle readers, besides the drivers' visual recognition of those signs.